1. Field of the Invention
The present invention relates to a dielectric ceramic composition used for a dielectric layer or so of an electronic component. Further specifically, the present invention relates to the dielectric ceramic composition and the electronic component using thereof which can lower a dielectric loss in a wide frequency range without including a lead (Pb) which is an environmental harmful material and bismuth (Bi) which the resource price is rising. Also the present invention relates to the dielectric ceramic composition and the electronic component using thereof having a relatively high dielectric constant while having a relatively good temperature characteristic, and also provides at lower cost.
2. Description of the Related Art
Recently, an environmental protection movement in a global scale has become more active, and thus in the electronic component field, it is demanded to reduce an environmental harmful material such as lead (Pb) or so. Therefore, there is a need for a development of an dielectric ceramic composition without a lead (Pb) but having characteristics at same level or better compared to one with a lead.
Also, since an electronic circuit constituting the electronic device has downsized and are more complicated, the electronic component mounted in the electronic circuit is demanded to be even more downsized and to have little self-heating to prevent a malfunction. Thus, even for a ceramic capacitor as one example of the electronic component, it is demanded to maintain a good temperature characteristic while having a high dielectric constant in order for the downsizing, and furthermore to have low dielectric loss in order to lower the self-heating.
On the other hand, due to the rising of the resource price, the manufacturing cost of the electronic component including a rare earth has also increased, however since a great deal of an amount of the electronic components are used in the electronic device, it is demanded to lower the price while maintaining a good ability.
Particularly, bismuth (Bi) is one of the rare earth that the price has recently increased, and it has been a problem for lowering the price of the electronic component. Also, bismuth (Bi) easily evaporates during a firing, and has been causing the characteristics to vary and to deteriorate the furnace material in the firing furnace.
Thus, the dielectric ceramic composition which does not include lead and also bismuth is demanded in order to obtain the electronic component having the high characteristics while satisfying the environmental protection and lowering the price.
For example, Japanese Patent No. 3767377 discloses the dielectric ceramic composition having a small dielectric loss within the high frequency range and also having good temperature characteristics. However, this dielectric ceramic composition includes lead and thus did not satisfy the demand of the environmental protection.
As the dielectric ceramic composition which does not include lead, for example Japanese Patent Application 2003-238240 discloses the dielectric ceramic composition obtained by adding at least one element among La, Nd, Ce, Sn, Zr, Ta, and Nb to a main component consisting of BaCO3, Bi2O3, and TiO2. However, the best dielectric loss of this dielectric ceramic composition shown at 1 MHz is 0.1 (10%) or so which is considered high; hence the self-heating was not sufficiently suppressed. Therefore, this dielectric ceramic composition could not effectively correspond to the demand for downsizing and complicating the electronic circuit for a raid-high voltage.
Furthermore, this dielectric ceramic composition includes bismuth, thus did not correspond to the demand of lowering the cost.